Optical noise in frequency-periodic networks

The problem of optical noise in partially-coherent optical networks is revisited, using the recently developed frequency-domain formulation. By applying this formulation to the important case of networks with a frequency-periodic transfer function (frequency-periodic networks) we derived a general expression for the output optical-noise power density spectrum. The general expression consists of an infinite sum of terms, which are expressed as products of two factors: one factor is derived from the network transfer function, and the other from the source statistical correlation functions. The source factors have been evaluated for the case of a random-phase source, which is used frequently to describe single-mode laser diodes. Simplified formulae were derived for several special cases of practical importance, and the Mach-Zehnder network was considered as an example